Insulator



Patented Mar. 12,1935

UNITED STATES PATENT OFFICE INSULATOR John J. Taylor, Barberton, Ohio,assignor to The Ohio Brass Company, Mansfield, Ohio, a corporation ofNew Jersey Application February 2, 1933, Serial No. 654,859

4 Claims. (01. 173-318) This invention relates to electric insulatorssecures the cap to the outer surface of the diand particularly toinsulators for supporting relelectric member. The cement is suitablybonded atively high mechanical loads for extended to the dielectricmember on its outer surface. periods of time without danger of failure.The cap is preferably provided with a plurality 5 One object of theinvention is to provide an of inwardly extending fins or ribs 20 tofacilitate 5 insulator having relatively high mechanical proper locationof the cap relative to the distrength and long life, and which will notbe electric member when the parts are assembled. injuriously affected bytemperature changes. It will be apparent that the opposed wedging Afurther object of the invention is to provide faces of the cap and pinwill tend to compress an insulator which shall be of improved contheporcelain a ment disposed between 10 struction and operation. thesefaces when a load is placed on the Other objects. and advantages willappear insulator. from the following description. The porcelain isrelatively hard and unyield- 'I he invention is exemplified by thecombiing as compared to the cement, and the disnation and arrangement ofparts shown in the tortion of the porcelain part is negligible. How- 15accompanying drawing and described in the folever, t cem Will yieldunder the Wedgihg lowing specification, and it is more particularlyaction of the bearin faces and Since the thickpointed out in theappended claims. ness of the interposed cement varies for differ- In thedrawing: ent positions along the tapered bearing faces,

0 Fig.1is anelevation with parts in section showthe amount of cushioningeffect produced by 'ing. one embodiment of the present invention. thecement will differ for different positions on F g. 2 is a fragmentarysection on line 2-2 these bearing faces, giving rise to an unequal ofdistribution of the stress on the bearing sur- Figs. 3. 4, 5 and 6 areelevations of the upper face of the porcelain. The cement has a strutends of modified forms of pins for use in action between the metal andthe porcelain 25 nection withthe insulator. which transmits the forcebetween these parts. Dielectric material such as porcelain, com- The1ehgth 0f the Cement Strut at the pp monly used for insulators, has highme h ni l edge of the surface 13, for instance, is less than strength incompression but is relatively weak it is at the lowe edge O this Surfaceand 1501 a in tension and shear. The present invention given movement ofthe P 11 downwardly 30 contemplates the support of the lo d on th underload, the total compression of the cement insulator largely bycompression on the dielec- Strut at the top of the sulfa- 1e 13 will bethe t C member. This is accomplished by providing same as the totalcompression at the bottom of the fittings. with opposed surfaces whichtend t s ut since the st at the p of to compress the dielectric materialbetween them. the Surface is much Shorter than at the bottom 35 n theform of the invention sh i Fig of the surface, the force transmitted tothe 1, the numeral 10 designates the dielectric memporcelain W ll begreater at h t p of e rber made of porcelain or other suitable mates fat a it l at t t u rial havingan attachment head provided ith tending toconcentrate the stress at the upper a recess for receiving a pin 11. Theinner end portions of the wedging bearing surfaces. 40 of the pin isdivided into a. plurality of steps; A similar concentration will beproduced at one of the steps having a conical bearing surface the loweredge of the bearing surface 18 on the 13, and the otherstep havingconical bearing cap. The resiliency of the cap will tend to ofisetsurfaces 14 and 15 disposed at different angles this concentration asthe lower edge will yield n t t th axis of th pin The pin ,1 somewhatunder the force and will relieve the 45 carries a resilient flange 16.The pin i Secured stress at this point. Moreover, the bearing surin arecess in the dielectric member by cement face of the p is h greaterthan that Of the 17 and the entire outer surface of the pin is P O thatthe Stress at any point CV61 the coated with wax or otherwise treated tpreouter portion of the dielectric member will be vent bonding betweenthe pin and the cement. ess t at the 1111191 poltioh- 00 The cement isbonded to the inner surface of In order to effect a distribution of thestress the recess in the dielectric member. The cap produced by the pthe Wedgihg bearing a e 12 is provided with an inclined bearing surfaceis divided into a plurality of steps. This will 18; the inside of thecap also being treated to give a uch better distribution than a Singleprevent bonding with the cement 19, which step having the same totalbearing surface as 55 different angularity.

member.

The conical or wedging caring faces on the metal fittings not only placethe porcelain under compression but also serve to compensate fordifferential expansion of the dielectric and metal parts, due totemperature changes. When the temperature falls, the loadon the pin willtend to draw the pin downwardly until checked by the conical bearingsurface. v The flange 16 and the cement shoulder below the flange willyield sufficiently to permit dcwnwardmovement of the pin 16. When thetemperature rises, the pressure on the outer face of the dielectricmember,-produced by the cap, will be relieved and the expansive force ofthe pin 11 will tend to burst the porcelain. If the frictionalengagement between the wedging faces 13, 14 and 15 and the cement weresufiicient to prevent return of the pin under the expansive force,injury to the porcelain would be apt to occur.

If reliance were placed entirely upon the lubricating effect of thecoating on the surfaces 13, 14 and 15, satisfactory return might occurfor a time but the lubricating material is apt to become displaced orlose its effectiveness in time, after which the pin might stick in itssocket and a rise in temperature would then be apt to burst thedielectric member. This danger is eliminated by the resilient flange 16,which assists the Wedging action of the surfaces 13, 14 and 15 inreturning the pin to its upper position when the expansive forceincreases.

The resilient flange 16 has another important function in the operationof the insulator, and this is to insure an adequate cap reaction beforeexpansive action is produced by the wedging I faces of the pin. When aload is placed upon the insulator pin, the initial portion of this loadis transmitted by the flange 16 before any substaru tial wedging actionis produced by the conical surfaces of the pin. This tends to draw thedielectric member and its attached cement 19 downwardly in the seat 18of the cap, producing a. cap reaction inwardly on the dielectric memberbefore an outward expansive force is brought to bear. The inwardpressure will always be kept in excess of the outward pressure and sincethe arch of the dielectric member produces a greater resistance toinward pressure than to outward pressure, the balance of pressure isalways kept in the right direction.

While the difference in angularity between the steps 14 and 15 improvesthe distribution of stress, it also produces direction of stress on thelower face'l5 not so advantageous as that of the other faces. The stressproduced by the face l5-will be'directed downwardly at a steeper anglethan that on the faces 13 and 14 and will be transmitted to the portionof the dielectric member below the cap 12 so that there is no abutmentportion of the cap for receiving this stress,

which consequently tends to produce tension in the dielectric member.The more abrupt angle of the face 15, however, makes possible a deepercut above the flange 16 for a given length of bearing surface than wouldotherwise be secured nd this is an advantage because it permits a.resilient flange of sufficient width to be located at a higher point onthe pin.

The advantage of the deeper notch above the flange 16 may be secured,without the disadvantage of the downwardly directed force from thesurface 15, by filling the opening between the flange 16 and the surface15 with a yielding material 21 which will exclude the cement from thisnotch, as shown in Fig. 3. This, however, will eliminate the action ofthe bearing face 15 in transmitting the force of the load to thedielectric member and distributing the load throughout the dielectricmaterial.

The resilient flange may be located still higher on the pin if a radialnotch is cut at the lower edge of the bearing surface 14, as shown at 22in Fig. 4. In this case it is very desirable to exclude cement from thenotch 22 by means of a yielding material 23 or other suitable expedient,so as to prevent the radial face at the lower edge of the flange 14 frombearing directly on a cement shoulder. This arrangement is especiallyadvantageous where a second resilient flange 25 is desirable or wheremore than two bearing steps are provided, as shown in Fig. 5.

.In Fig. 5, 3 steps 26, 27 and 28 are shown, and a single resilientflange 29 is located below'the bearing steps and separated from them bya notch .22, filled with yielding material 23.

Fig. 6 combines the characteristics of Figs. 1 and 5 in that it providesa plurality of bearing surfaces 30, 31 and 32, these surfaces beingdisposed at various angles relative to the axis 01 the pin so as toimpart a compression to the cement struts more nearly proportional tothe length of the struts. The upper bearing surface 30, for instance,may have an inclination of 20 degrees to the axis of the pin, while thesecond surface 31 has an inclination of 30 degrees, and the lowersurface an inclination 0140 degrees. A resilient flange 16 is provided,as in Fig. 1. With a pin of this kind, the stress will be distributedapproximately uniformly over the active portion of the dielectricmaterial'and the resilient flange 16 will not only insure establishmentof cap reaction prior to expansive force exerted by the wedging pinsurfaces under the load on the insulator, but will also insure movementof the pin in its socket to compensate for temperature changes. It willbe understood that in all cases the portion of the pin in the cementbelow the bearing flanges is sufficiently relieved to preventinterference with the action of the bearing faces.

I claim:

1. An insulator comprising a dielectric member having a recess therein,a pin having an attachment head disposed in said recess and providedwith a rigid, bearing surface tapered inwardly toward the free end ofthe pin, said bearing surface having portions disposed at differentangles relative to the axis of the pin, the angle of each portionrelative to the axis of the pin being greater than the angle of theportion next adjacent thereto toward the inner end of the pin, cementdisposed in said recess about said head, and a resilient flange on saidpin and engaging said cement and disposed next adjacent to, but spacedfrom, the portion of said bearing surface having the greatest angle withthe axis of said pin, to provide for a deep groove between said flangeand bearing surface.

2. An insulator comprising a dielectric member having a recess therein,a pin having a bearing head disposed in said recess, said bearing headhaving a plurality of rigid, bearing surfaces thereon tapered inwardlytoward the free end of the pin, cement interposed about said head withinsaid recess, said pin being unbonded to said cement, one of said bearingsurfaces having a less maximum diameter and a greater angle relative tothe axis of the pin than another cf said surfaces farther within saidrecess, and a resilient flange secured to said pin and engaging saidcement for restoring said pin to its initial position when displacedtherefrom said flange being disposed next adjacent, but spaced from, thebearing surface of greatest angle with the axis, to provide a deepgroove between said flange and surface.

3. An insulator comprising a dielectric member having an attachment headthereon, a cap enclosing said head, cement interposed between said capand head, said cap having a conical bearing face, the surface of saidcap being unbonded to said cement, a pin having a bearing head disposedin a recess in said dielectric member, said head having a plurality ofrigid, bearing faces tapered inwardly toward the free end of the pin,one of said faces having a greater angle relative to the axis of the pinand having a less maximum diameter than another face farther within saidrecess, cement disposed in said recess about said pin, said pin beingunbonded to said cement, and a resilient flange on said pin spaced fromsaid bearing faces toward the free end of the pin and engaging saidcement for transmitting the initial portion of the load on said pin tosaid insulator to insure initial cap reaction before excessive wedgingaction is produced by the bearing surfaces of the pin and to facilitatemovement of the pin to compensate for differential expansion andcontraction due to temperature changes the bearing face having thegreatest angle with said axis being next adjacent said flange to providefor a deep groove adjacent said flange.

4. An insulator comprising a dielectric member having an attachment headprovided with a recess, a pin having one end thereof disposed in saidrecess and having a rigid, conical bearing surface tapered inwardlytoward the free end of the pin, a cap surrounding said head and having aconical bearing surface opposed to and tapered in the same direction asthe bearing surface of said pin, cement securing said cap and pin tosaid head, said cap and pin being unbonded to said cement, a portion ofthe bearing surface of said pin having a greater angle relative to theaxis of the pin than another portion of said surface farther within saidrecess, and a resilient flange below and next adjacent to the portion ofthe bearing surface of said pin having the maximum angle with said axisand engaging said cement to insure initial cap reaction prior toexcessive expansive force exerted by the bearing surface of said pin,and to facilitate movement of said pin to compensate for temperaturechanges.

JOHN J. TAYLOR.

